In sensory systems most of the precise wiring of visual connections occurs during a postnatal time window of brain development known as the critical period. During this time window, brain connections become highly specified through the selective elimination of ineffective synapses and the maintenance of the correct ones. Omega-3 fatty acids are exclusively acquired through the diet, and thus blood levels are directly influenced by their dietary availability. These essential fatty acids are transferred through the placenta and are also present in human milk. Therefore, these fatty acids are substantially accumulated in the brain and retina during the fetal period and early postnatal development. Studies have shown that the deprivation of omega-3 fatty acids results in deficits not only in visual acuity but also in cognition. We discuss the role of omega-3 fatty acids in the development of sensory connections, the consequences of its nutritional restriction in animal models and the impact of such nutritional imbalance in the development of motor and cognitive skills.